Biweekly Cetuximab Plus FOLFOX6 as First-Line Therapy in Patients With RAS Wild-Type Metastatic Colorectal Cancer: The CEBIFOX Trial.

Background: The multicenter, single-arm, phase II study CEBIFOX evaluated the efficacy of a biweekly cetuximab administration in combination with FOLFOX6 as first-line therapy in KRAS (exon 2) wild-type (wt) metastatic colorectal cancer (mCRC).
Patients and Methods: Patients received FOLFOX6 with cetuximab (500 mg/m ² ) every second week. Primary endpoint was objective response rate (ORR), among others secondary endpoints were safety, progression-free survival (PFS), overall survival (OS), and patient-reported outcome (PRO). The impact on the treatment efficacy was evaluated in explorative subgroup analyses, including extended molecular profiling and primary tumor location.
Results: In total, 57 were included in the intention-to-treat (ITT) analyses. New RAS mutations were detected in 14.0% by post hoc next-generation sequencing analysis in 43 patients. The ORR in the all RASwt population was 70.3% with a median PFS and OS of 10.9 (95% confidence interval [CI], 9.0-12.9) and 33.8 (95% CI, 21.1-45.5) months. Grade 3-5 adverse events occurred in 66.7% of the ITT, without significant impact on the PRO. Patients with right-sided primary tumors had a reduced ORR (54.5%), and median PFS and OS (10.1 and 23.8 months). BRAF mutations were detected in 11.3%. These patients had a significantly lower ORR, and median PFS and OS. Patients with RASwt/BRAFwt tumors had a notably high median PFS and OS of 14.3 and 38.9 months.
Conclusions: This study supports the efficacy and safety of biweekly cetuximab given in combination with FOLFOX6 in patients with RASwt/BRAFwt mCRC with left-sided primary tumor. CEBIFOX is the first trial reporting the complete dataset, including extended molecular profiling and tumor location of a biweekly administered cetuximab/FOLFOX6 in mCRC. Clinical trial number: NCT01051167.
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